Heat the oven to 180°C with a fan and line a baking tray with baking paper.
Unroll the prepared pastry and cut out heart shapes using a 4-inch heart cutter. Place the hearts on the prepared baking tray, leaving space between them.
Bake for 12–15 minutes, or until well risen and golden. Remove from the oven and let them cool completely.
Remove the stems from the strawberries and slice them.
In a large bowl, whip the double cream with the vanilla and icing sugar until it is thick and suitable for piping.
Cut each heart pastry in half horizontally. Pipe a layer of cream on the bottom, leaving a small gap in the middle and put the jam. Add some strawberry and raspberry slices, then pipe another layer of cream. Place the pastry lid on top. Dust lightly with icing sugar and serve.
